marine mercury barometer
Datec.1920
Inventory NumberDW0643
ClassificationBarometer
Subject
Maker
Henry J. Green
fl. 1885 - 1910
User
Institute of Geographical Exploration
1929 - 1952
Cultural Region
Place of Origin
Place of Use
Material
DescriptionThis marine mercury barometer, possibly a Kew Pattern barometer, is mounted in a rectangular mahogany wall mounting with gimbals and a swinging arm.
The instrument consists of a glass filled tube of mercury under a vacuum, ending in a mercury filled cistern of fixed volume. The screw in the center of the staff controls a sliding vernier. There is a small metal hoop at the top.
The contracted case scale runs from 26 1/2" to 32 1/2 ", and the thermometer, below the barometric scale, runs from 10-120 (°F).
The instrument consists of a glass filled tube of mercury under a vacuum, ending in a mercury filled cistern of fixed volume. The screw in the center of the staff controls a sliding vernier. There is a small metal hoop at the top.
The contracted case scale runs from 26 1/2" to 32 1/2 ", and the thermometer, below the barometric scale, runs from 10-120 (°F).
Signedon cistern: Henry J. Green / B'KLYN N.Y; on scale: 4753; on thermometer: 27708
Inscribedalong side of staff: H. J. Green B'KLYN N.Y.
FunctionA marine barometer has to overcome the special challenges of being read and transported at sea. Gimbals would have kept the instrument relatively stationary and vertical despite the motion of the sea. The contracted scale also accounts for inaccuracies in reading air pressure at sea.
The barometer would have been mounted securely against a wall from its swinging arm and gimbals. A reading from the outer scale is taken at the top of the mercury column, which is forced upwards from the pressure of the air on the cistern. The sliding vernier would have been used take more accurate measurements for values between those on the main scale. The thermometer would have been used to correct for variations due to temperatures other than the standard.
The barometer would have been mounted securely against a wall from its swinging arm and gimbals. A reading from the outer scale is taken at the top of the mercury column, which is forced upwards from the pressure of the air on the cistern. The sliding vernier would have been used take more accurate measurements for values between those on the main scale. The thermometer would have been used to correct for variations due to temperatures other than the standard.
ProvenanceDavid Wheatland purchased from the Harvard Geography Building (Institute of Geographical Exploration), February 1959.
C. F. Casella & Co. Ltd.
Date: circa 1920
Accessories: Card and tags indicate there should be a leather carrying case, strap, and 3 legs for support. However, this instrument has been stored by itself.
Object number: DW0642
Johann Georg Greiner, Jr.
Date: circa 1850
Accessories: white wood case in leather cover; scale on rack & pinion, vernier, and two magnifiers; Reaumur thermometer
Object number: DW0758
Johann Georg Greiner, Jr.
Date: circa 1850
Accessories: case; loose padding for instrument in case
Object number: DW0759
